Add the Menubar to the Titlebar in MacOS (#3751)

* Add the Menubar to the Titlebar in MacOS

* Remove obsolete Swing menubar stuff

src/main/java/org/jabref/JabRefGUI.java

@@ -34,7 +34,6 @@
 import org.jabref.logic.l10n.Localization;
 import org.jabref.logic.shared.exception.InvalidDBMSConnectionPropertiesException;
 import org.jabref.logic.shared.exception.NotASharedDatabaseException;
-import org.jabref.logic.util.OS;
 import org.jabref.logic.util.Version;
 import org.jabref.model.database.shared.DatabaseNotSupportedException;
 import org.jabref.preferences.JabRefPreferences;
@@ -74,12 +73,6 @@ public static void checkForNewVersion(boolean manualExecution) {
     }
 
     private void openWindow(Stage mainStage) {
-
-        // This property is set to make the Mac OSX Java VM move the menu bar to the top of the screen
-        if (OS.OS_X) {
-            System.setProperty("apple.laf.useScreenMenuBar", "true");
-        }
-
         // Set antialiasing on everywhere. This only works in JRE >= 1.5.
         // Or... it doesn't work, period.
         // TODO test and maybe remove this! I found this commented out with no additional info ( payload@lavabit.com )

src/main/java/org/jabref/gui/JabRefFrame.java

@@ -741,7 +741,6 @@ public void setTabTitle(BasePanel comp, String title, String toolTip) {
      */
     private MenuBar createMenu() {
         ActionFactory factory = new ActionFactory(Globals.getKeyPrefs());
-
         Menu file = new Menu(Localization.menuTitle("File"));
         Menu edit = new Menu(Localization.menuTitle("Edit"));
         Menu library = new Menu(Localization.menuTitle("Library"));
@@ -1011,6 +1010,7 @@ private MenuBar createMenu() {
                 view,
                 options,
                 help);
+        menu.setUseSystemMenuBar(true);
         return menu;
     }